Wedge clutch with wedge chain

ABSTRACT

A wedge clutch includes an inner race and an outer race. The outer race defines an inner cam surface. A chain of wedges encircles the inner race and are configured to couple the races when the clutch is engaged. The wedges have outer surfaces that match with sections of the inner cam surface such that the wedges have an outer radial position when in first rotational position relative to the cam surface and have an inner radial position when in a second rotational position to frictionally engage the inner race.

TECHNICAL FIELD

The present disclosure relates to clutches configured to couple rotatingmembers, and more specifically to clutches that include a wedge element.

BACKGROUND

A clutch is a component used to selectively couple two or morecomponents such as rotatable shafts. The clutch may be engaged to couplethe components and may be disengaged to decouple the components. Manytypes of clutches are known. One type of clutch is a wedge clutch. Awedge clutch may include an inner race connected to a shaft and an outerrace connected to another shaft. A wedge plate is radially disposedbetween the inner and outer races and is configured to couple the innerand outer races when the clutch is engaged to transmit power from oneshaft to another.

SUMMARY

According to one embodiment, a wedge clutch includes an inner race andan outer race. The outer race defines an inner cam surface. A chain ofwedges encircles the inner race and are configured to couple the raceswhen the clutch is engaged. The wedges have outer surfaces that matchwith sections of the inner cam surface such that the wedges have anouter radial position when in first rotational position relative to thecam surface and have an inner radial position when in a secondrotational position to frictionally engage the inner race.

According to another embodiment, a wedge clutch includes an inner race,an outer race, and an annular wedge assembly radially disposed betweenthe inner and outer races. The wedge assembly is configured toselectively couple the races and includes a plurality of segmentscircumferentially arranged around the inner race. Each segment has apair of first and second wedge stacks interconnected to each other by afirst link, and each of the wedge stacks has multiple wedges that areaxially spaced relative to each other. A plurality of second links areeach connected between adjacent ones of the segments to interconnect thesegments to form a chain.

According to yet another embodiment, a clutch includes an inner racedefining at least one groove and an outer race defining an inner camsurface. A wedge chain is radially disposed between the inner and outerraces. The wedge chain includes a plurality of wedges disposed in the atleast one groove and interconnected with links to encircle the innerrace. Each of the wedges have an outer surface that cooperates with thecam surface to increase and decrease friction between the wedge and theat least one groove in response to circumferential movement of the wedgerelative to the cam surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a wedge clutch.

FIG. 2 is a perspective view of a wedge chain of the wedge clutch.

FIG. 3 is a cross-sectional view of the wedge clutch.

FIG. 4 is a perspective view of the wedge clutch.

FIG. 5 is a partial perspective view of another wedge clutch accordingto an alternative embodiment.

FIG. 6 is a flow chart illustrating a method of assembling a wedgeclutch.

FIG. 7 is a flow chart illustrating a method of assembling a wedgechain.

FIG. 8 is a side view showing an assembly step of the method of FIG. 7in which a pair of wedges are aligned with a link.

FIG. 9 is a diagrammatical top view showing an assembly step of themethod of FIG. 7 in which pins are driven into the pair of wedges ofFIG. 8.

FIG. 10 is a side view showing a completed chain assembled according tothe method of FIG. 7.

FIG. 11 is a flow chart illustrating a method of assembling a wedgechain according to an alternative embodiment.

DETAILED DESCRIPTION

Embodiments of the present disclosure are described herein. It is to beunderstood, however, that the disclosed embodiments are merely examplesand other embodiments can take various and alternative forms. Thefigures are not necessarily to scale; some features could be exaggeratedor minimized to show details of particular components. Therefore,specific structural and functional details disclosed herein are not tobe interpreted as limiting, but merely as a representative basis forteaching one skilled in the art to variously employ the embodiments. Asthose of ordinary skill in the art will understand, various featuresillustrated and described with reference to any one of the figures canbe combined with features illustrated in one or more other figures toproduce embodiments that are not explicitly illustrated or described.The combinations of features illustrated provide representativeembodiments for typical applications. Various combinations andmodifications of the features consistent with the teachings of thisdisclosure, however, could be desired for particular applications orimplementations.

Many vehicles and other applications require selective coupling of twoor more members such as shafts, gears, transmissions, torque converters,electric motors, and the like. A clutch is a mechanism configured toselectively couple two or more members. The clutch may couple a pair ofrotating members, or may couple a rotating member to a stationarymember, in which case the clutch is commonly referred to as a brake. Inone example application, the clutch may be used in a hybrid vehicle todisconnect an internal-combustion engine from a hybrid transmission. Ofcourse, the clutch may be used in a variety of other applications suchas in a stator of a torque converter.

Referring to FIGS. 1 and 2, a clutch 20, which is known as a wedgeclutch, may be used to couple two or more components. The clutch 20includes an inner race 22 (also known as a hub) and an outer race 24(also known as a carrier). A wedge assembly 26 is radially disposedbetween the inner and outer races 22, 24 and is configured toselectively couple the races. The clutch 20 may include a plurality ofmodes that couple and decouple the races 22, 24 in a variety of relativedirections of rotation. For example, the clutch 20 may include a fullylocked mode (also known as lock-lock mode) in which the races 22, 24 arecoupled in both rotational directions and at least one one-way mode(also known as lock-free mode) in which the races 22, 24 are coupled ina first rotational direction and are decoupled, i.e., overrun, in asecond rotational direction that is opposite the first. The clutch 20may include two one-way modes so that the overrunning direction can beswitched to suit current operating conditions and may include anunlocked mode (also known as open mode) in which the races 22, 24 arecompletely decoupled. The clutch 20 may be biased to the fully lockedmode, a one-way mode, or an unlocked mode. The specific modes offered,and the bias of the clutch, can be modified to suit specificapplications. The hardware illustrated in FIG. 1 is capable of offeringall of the above described modes when suitably combined with the correctactuator and control logic.

The clutch 20 may be supported in a housing (not shown) that isattachable to a support structure such as a vehicle chassis or otherfixed member. The inner and outer races 22, 24 may be supported forconcentric rotation within the housing. The housing may define a seatthat receives a roller bearing that in turn supports the outer race 24for rotation within the housing. The outer race 24 may be connectable toa rotating member, or alternatively a stationary member, via a splineconnection, fasteners, press-fit, or the like. Similarly, the inner race22 is connectable to a rotating member, or alternatively a stationarymember, via spline connection, fasteners, press-fit, or the like.

A wedge assembly 26 includes a plurality of individual wedges 30 thatcooperate to couple and decouple the inner and outer races 22, 24. Thewedges 30 may be generally arcuate as shown in the illustratedembodiment. To facilitate manufacturability of the clutch 20, theindividual wedges 30 may be assembled as a chain. Assembling the wedgeassembly 26 as a chain holds the individual wedges 30 in place while thewedge assembly 26 is installed on the inner and outer races. The chain26 is wrapped around the inner race 22 to place the wedges 30circumferentially around the inner race 22.

Each wedge 30 has a circular inner diameter 32 that substantiallymatches the outer diameter 34 of the inner race 22 and an outer surface36 that is ramped, to conform with the shape of an inner cam surface 38formed on the outer race 24, causing the wedges 30 to taper in heightalong the arcuate direction of the wedge 30. In the illustratedembodiment two types of wedges 30 a and 30 b are used, but in otherembodiments, each of the wedges may be the same. The wedges 30 a and 30b may be similar except that wedges 30 a include a tail 35. Like wedgesare arranged with each other in wedge stacks. For example, four wedges30 a are grouped together to form a wedge stack 40 a and four wedges 30b are grouped together to form a wedge stack 40 b. Spacers 42 are placedbetween the wedges in the wedge stacks to axially space the wedges fromeach other. In the illustrated embodiment, three spacers are in eachwedge stack 40 a, 40 b. The wedge stacks may include more or less wedgesand spacers in other embodiments.

The wedge stacks 40 a, 40 b are installed in the clutch in either afirst orientation or a second orientation that is mirrored relative tothe first orientation. (The first and second orientations are mirroredover a radially extending line.) Each of the wedge stacks 40 a may be inthe same orientation, and each of the wedge stacks 40 b may be in thesame orientation.

The wedge stacks 40 a, 40 b are arranged in pairs that form segments 44of the chain 26. Each segment 44 includes a wedge stack 40 a that is inthe first orientation and a second wedge stack 40 b that is in thesecond orientation. The wedge stacks 40 a may be referred to as a firstset and the wedge stacks 40 b may be referred to as a second set. Thefirst and second sets of wedge stacks alternate along the length of thechain 26 and around the circumference of the inner race 22 wheninstalled.

The stacks 40 a, 40 b of each pair are connected to each other by a link46. The links 46 are designed to allow a certain degree of movementbetween the wedge stacks. For example, the links 46 may allow pivotaland circumferential movement between the stacks 40 a, 40 b. The links 46may include pins 50 that extend through slots 48 defined in the wedges30 and the slots 49 of the spacers 42. Side plates 52 of the links 46interconnect the pins 50. The slots 48 may be elongated in thecircumferential direction to facilitate the circumferential movement ofthe wedges 30. A resilient member 54 may be disposed between the stacks40 a, 40 b of each segment 44 to bias the stacks away from each other.In the illustrated embodiment, the resilient members 54 may be springsthat are received over the links 46. Thus, the links 46 may be referredto as spring links.

The segments 44 may be joined together by links 56. The links 56 may besimilar to the links 46 and include pins 58 that are received throughslots 62 defined in the wedges 30, slots 63 in the spacers, and sideplates 60 that interconnect the pins 58. The links 56 allow the segments44 to move relative to each other. For example, the pin connectionallows the segments 44 to pivot relative to each other and the slots 62may be elongated in the circumferential direction allowing the segments44 to move circumferentially relative to each other. The side plates 60are designed to allow a finger of an actuator to be received between thesegments 44. Thus, the links 56 may be referred to as actuator links. Amiddle portion of the side plates 60 may dip radially inward providingclearance for the finger. (Example actuation will be described below inmore detail.)

Referring to FIG. 3, the inner race 22 may have a plurality of axiallyspaced circular grooves 70 defined in the outer diameter 34. The grooves70 are spaced to match the axial spacing of the wedges 30 in the wedgestacks 40 a, 40 b. Each of the grooves 70 receives a corresponding oneof the rows 72 of wedges of the chain 26. That is, the chain 26 iswrapped around the outer diameter 34 so that the inner surfaces 32 ofthe wedges 30 are received within the grooves 70. The grooves 70 and theinner surfaces 32 are designed to frictionally lock with each other whenthe clutch 20 is engaged.

Referring to FIG. 4, the inner cam surface 38 includes lobes 80 andvalleys 82 interleaved with the lobes 80. The lobes 80, are theinner-most portion of the cam surface 38 and the valleys 82 are theouter-most portion of the cam surface 38. Ramps 84 each extend betweenadjacent ones of the lobes 80 and the valleys 82. Each set of ramps,lobes, and valleys collectively defines a generally wedge-shaped pocket85 in the outer race 24 for receiving one of the wedge stacks 40 a, 40b.

Each of the wedge stacks 40 a, 40 b is seated in one of the pockets 85with the outer surface (outer edge) 36 facing a ramp 84, a short end 90facing a lobe 80, and a tall end 92 facing a valley 82. The outersurface 36 is ramped to match the ramps 84 so that the wedges 30 canslide along the inner cam surface 38. The wedges 30 may be biasedtowards the lobes 80 via the springs 54 so that the clutch 20 is in thefully locked mode by default.

The clutch 20 operates by wedging the wedges 30 into the inner race 22to create a friction coupling. The wedges 30 may be biased toward thelobes 80 by the resilient members 54. This creates friction between thewedges 30 and the inner race 22, which causes the wedges 30 todecelerate relative to the outer race 24 and further slide in a wedgingdirection of the cam surface 38 when power is applied to the clutch 20.That is, at least some of the decelerating wedges 30 ride down the ramps84 increasing the friction between the wedges 30 and the inner race 22to create a friction coupling sufficient to lock the inner and outerraces 22, 24. The cam surface 38 is shaped so that the wedges 30 cannotpass over the lobes 80 to lock the outer race 24 to the wedge assembly26. This creates a power flow path through the clutch 20 so that powercan be selectively transferred between the components attached to theraces 22, 24.

The wedge stacks 40 a and 40 b cooperate with the inner cam surface 38to selectively couple the inner and outer races 22, 24 depending uponthe positions of the wedge stacks 40 a and 40 b on the inner cam surface38. The chain 26 is configured to allow movement between the wedgestacks allowing the different sets of stacks 40 a, 40 b to be indifferent locations on the cam surface 38. Each set of the wedge stacksmay be responsible for coupling the inner and outer races 22, 24 in oneof the rotational directions. For example, the first set of wedge stacks40 a can prevent the inner race 22 from rotating in a first direction 55relative the outer race 24 and the second set of wedges 40 b can preventthe inner race 22 from rotating in a second direction 57 relative theouter race 24 depending upon the location of the wedge stacks on theinner cam surface 38.

The wedge stacks 40 a, 40 b may be controlled by an actuator (notshown). A variety of different actuators may be used includingelectromagnetic, hydraulic, and mechanical. The actuator may includefingers that are disposed between the segments 44. The fingers may bemounted to a disk and included as part of the clutch 20. The disk may berotated relative to the outer race 24 to circumferential move associatedwedge stacks via the fingers to engage and disengage the wedge stackswith the inner race 22. Applicant's U.S. patent application Ser. No.16/050,782, filed Jul. 31, 2018, describes examples of this type ofactuator and is incorporated in its entirety by reference herein.

Another type of actuator may include variable-width fingers disposedbetween the segments 44. The fingers may be moved axial to adjust thecircumferential position of the wedge stacks to engage and disengage theclutch. Applicant's U.S. patent application Ser. No. 16/037,457, filedJul. 17, 2018 describes examples of this type of actuator and isincorporated in its entirety by reference herein.

An example will now be described to explain operation of the clutch 20in the fully locked mode. Assume that the outer race 24 is attached tothe driving shaft and the inner race 22 is attached to the driven shaft.The wedges 30 a prevent the inner race 22 from rotating in the firstdirection 55 relative to the outer race 24 as the drag force between thewedges 30 a and the inner race 22 causes the ramps 84 and the outersurface 36 to ride up each other to create sufficient friction betweenthe wedges 30 a and the inner race 22 to lock the inner race 22 to theouter race 24. Similarly, the wedges 30 b prevent the inner race 22 fromrotating in the second direction 57 relative to the outer race 24. Thus,the wedge stacks 40 a and 40 b cooperate to lock the inner race 22 tothe outer race 24 in both directions.

Continuing with the above example, the clutch 20 may be switched fromthe fully locked mode to a one-way mode by circumferentially moving oneset of the wedge stacks towards the valley's 82. For example, drivingthe wedge stacks 40 b towards the valleys 82 decreases or eliminates thefriction between the wedges 30 b and the inner race 22 so that the innerrace 22 can overrun in the second direction 57. A second one-way modecan be achieved by releasing the driving wedge stacks 40 b and drivingthe wedge stacks 40 a towards the valleys 82 to decrease or eliminatethe friction between the wedges 30 a and the inner race 22 so that theinner race 22 can overrun in the first direction 55.

The clutch 20 may be fully disengaged by moving the wedge stacks 40 a,40 b towards the valleys 82 to reduce the friction force between thewedges 30 a, 30 b and the inner race 22 to a nominal amount.

One of many ways to increase torque capacity of the of the clutch 20 isto increase or decrease the number of wedge rows of the wedge assembly26. In the above illustrated embodiment, the wedge assembly 26 includedfour rows of wedges, which is suitable for relatively high-torqueapplications. For lower-torque applications, the number of rows can bereduced to two or in some instances one.

FIG. 5 illustrates a lighter-duty clutch 100 that has a single row ofwedges. The clutch 100 may include an inner race 101 and a wedgeassembly (wedge chain) 102. The wedge assembly 102 includes a pluralityof wedges 104 that may be the same or similar to the wedges 30. Thewedges 104, like above, are arranged in mirrored pairs to form segments106. The wedges 104 of each pair are joined together by a link 108. Thelinks 108 may be similar to the above-described links except designed toconnect single wedges as compared to wedge stacks. Springs 110 may bedisposed over the links 108 to bias the wedges 104 of each pair awayfrom each other. Also like above, the wedge segments 106 may be joinedtogether by links 112 to form a chain having a single row of wedges 104.The inner race 101 may define a single circular groove in the outerdiameter that receives an inner surface of the wedges 104.

The remaining components of the clutch may be like the clutch 20 albeitmodified to match the axial thickness of the single row chain 102. Thewedge clutch 100 may operate in the same manner described above.

The above-described clutches and wedge chains may be manufactured andassembled in many different ways. Below are example methods forassembling the wedge chains and wedge clutches. The below methods aremerely examples and are not an exhaustive list of suitable manufacturingprocesses.

Referring to FIG. 6, a method 200 of assembly generally includesassembling a wedge chain by connecting a plurality of wedges togetherwith links such that the wedges are movable relative to each other atstep 202. At step 204, the wedge chain is wrapped around an inner race.The ends of the chain are connected at step 206 to secure the chain tothe inner race. The inner race may define one or more circular groovesthat partially receive the wedges of the chain. FIG. 5 shows an examplesubassembly after step 206. The ends may be connected by securing an endone of the links to an end one of the wedges. The end one of the linksmay be an ordinary link, or in some embodiments, a master link may beused. A master link is a quick-release link that allows for convenientconnection and disconnection of the chain. Master links may be designedto be connected/disconnected without the need for special tools. At step208, the inner race is installed into an outer race with the wedge chainbeing radially disposed between the races. The inner race may beinstalled by aligning the wedge chain with an inner cam surface of theouter race and then inserting the inner race and the wedge chain intothe outer race so that the wedges nest with the inner cam surface. FIG.4 shows an example clutch after step 208. After step 208, the corecomponents of the clutch have been assembled. Additional components,such as actuators, shafts, housings, and the like, may then be assembledto the core components to complete clutch assembly.

Referring to FIGS. 7 through 10, a method 250 of assembling a single-rowwedge chain 240 will be described according to one embodiment. At step252 a plurality of wedges are provided. The wedges may include a firsttype of wedges 212 and a second type of wedges 214. The wedges may bethe same or similar as wedges 30 a and 30 b described above. In someembodiments, the wedges may all be the same type. The wedges may beformed from a metal alloy and may be manufactured using a stampingprocess or other known technique. The slots 216, 218 may be formedduring the stamping process or may be formed in a secondary operation.The wedges 212, 214 may be manufactured by the entity that produces thewedge chain or by another entity.

A chain of wedges may be assembled by loading a plurality of wedges,links, and other components into one or more tools that sequentiallyattach adjacent wedges to each other to build the chain in a linearprocess. At step 254, a pair of wedges may be positioned adjacent toeach other with the wedges being in a mirrored orientation as shown inFIG. 8. Side plates 220, 222 of a link 224 are aligned with the wedges212, 214 so that holes of the side plates 220, 222 are aligned with theslots 216. A resilient member 226, such as a coil spring, may bedisposed over the side plates 220, 222 to engage between the wedges 212,214. Pins 228 are driven through the side plates and the wedges to fullyform the link 224 and secure the pair of wedges 212, 214 to each otherat operation 256 as shown in FIG. 9. This process may be repeated withsuccessive wedges and links to form a chain of desired length. In theillustrated embodiment of FIG. 10, the chain includes two types oflinks, the above-described links 224 that include a resilient member anda second type of link 230 that does not include a resilient member. Thelinks 224 and 230 may be the same or similar to the above-describedlinks 46 and 56. This is but one example process for assembling a wedgechain and others are contemplated. For example, the links may bepartially assembly as a side plate with two projecting pins. A pair ofwedges may be assembled to the link by inserting the pins into theirrespective slots. A second side plate may then be secured to the pins toclose the link and fully attached the pair of wedges. This process maybe repeated to build a chain of desired length.

Referring to FIG. 10, the chain 240 is assembled with circular inneredges 242 of the wedges 212, 214 all facing in the same direction andthe outer ramped edges 244 all facing the same direction so that all ofthe inner edges 242 are received on the inner race and all of the rampededges engage with the outer race when the chain 240 is installed. Theouter ramped edges 244 collectively define a discontinuous outer camsurface of the chain 240 when wrapped around the inner race. Thediscontinuous outer ramped surface conforms in shape with the inner camsurface of the outer race. The orientations of the wedges 212, 214alternate along a length of the chain 240 such that placements of thetall ends 246 and the short ends 248 of adjacent ones of the wedges areflipped.

Referring to FIG. 11, a method 300 of assembling a multi-row wedge chain(such as that depicted in FIG. 2) will now be described. Similar to thesingle-row chain 240, the multi-row wedge chain may be assembled byloading at least a plurality of wedges, links, spacers, and pins andsequentially assembling and attaching wedge stacks to each other. Atstep 302, a plurality of wedges and a plurality of spacers may beassembled into at least two wedge stacks so that spacers alternate withthe wedges in an axial direction of the clutch (width direction ofchain). At least two of the wedge stacks are arranged adjacent to eachother in a mirrored orientation at step 304. At step 306, a first linkis attached between the adjacent wedge stacks. The first link mayinclude a resilient member and have a structure similar to the link 46described above. The first link may be attached to the wedge segments byaligning side plates of the link with the wedge segments and spacers,and driving pins therethrough similar to the method 250. At step 308another wedge stack may be assembled and then attached to the chain by asecond link at step 310. This process is repeated until a desired numberof wedge stacks are assembled onto the chain. FIG. 2 illustrates oneexample embodiment of a wedge chain (wedge assembly) produced using themethod 300. In the illustrated embodiment the first and second links aredifferent types of links, but in other embodiments the chain may onlyinclude a single type of link.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms encompassed by the claims.The words used in the specification are words of description rather thanlimitation, and it is understood that various changes can be madewithout departing from the spirit and scope of the disclosure. Aspreviously described, the features of various embodiments can becombined to form further embodiments of the invention that may not beexplicitly described or illustrated. While various embodiments couldhave been described as providing advantages or being preferred overother embodiments or prior art implementations with respect to one ormore desired characteristics, those of ordinary skill in the artrecognize that one or more features or characteristics can becompromised to achieve desired overall system attributes, which dependon the specific application and implementation. These attributes caninclude, but are not limited to cost, strength, durability, life cyclecost, marketability, appearance, packaging, size, serviceability,weight, manufacturability, ease of assembly, etc. As such, to the extentany embodiments are described as less desirable than other embodimentsor prior art implementations with respect to one or morecharacteristics, these embodiments are not outside the scope of thedisclosure and can be desirable for particular applications.

The following is a list of reference numbers shown in the Figures.However, it should be understood that the use of these terms is forillustrative purposes only with respect to one embodiment. And, use ofreference numbers correlating a certain term that is both illustrated inthe Figures and present in the claims is not intended to limit theclaims to only cover the illustrated embodiment.

PARTS LIST

-   -   20 Clutch    -   22 inner race    -   24 outer race    -   26 wedge assembly (chain)    -   30 wedges    -   30 a wedge    -   30 b wedge    -   32 inner surface    -   34 outer diameter    -   35 tail    -   36 outer surface    -   38 inner cam surface    -   40 a, 40 b wedge stacks    -   42 spacers    -   44 segments    -   46 spring links    -   48 slots    -   49 slots    -   50 pins    -   52 side plates    -   54 spring    -   56 actuator links    -   58 pins    -   60 side plates    -   62 slots    -   63 slots    -   70 grooves    -   72 rows    -   80 lobes    -   82 valleys    -   84 ramps    -   90 short end    -   92 tall end    -   100 clutch    -   102 wedge assembly    -   104 wedges    -   106 segments    -   108 links    -   110 springs    -   112 links

What is claimed is:
 1. A wedge clutch comprising: an inner race; anouter race defining an inner cam surface; and a chain of wedgesincluding segments each having a pair of the wedges joined together by afirst type of link, the chain further including a second type of linksthat interconnect the segments, wherein the chain encircles the innerrace and is configured to couple the races when the clutch is engaged,the wedges having outer surfaces that match with sections of the innercam surface such that the wedges are in an outer radial position when ina first rotational position relative to the cam surface and are in aninner radial position when in a second rotational position relative tothe cam surface, wherein the wedge clutch is engaged when in the secondrotational position and is disengaged when in the first rotationalposition.
 2. The wedge clutch of claim 1, wherein the wedges of eachsegment are in a mirrored orientation relative to each other.
 3. Thewedge clutch of claim 1, wherein the first type of link includes aresilient member that basis-biases the wedges of the pair away from eachother.
 4. The wedge clutch of claim 1, wherein the wedges are movablerelative to each other in a circumferential direction.
 5. The wedgeclutch of claim 1, Wherein each of the wedges defines at least one slotgenerally elongated in a circumferential direction of the clutch, andwherein the first and second types of links have pins disposed in theslots.
 6. The wedge clutch of claim 1, Wherein the inner race defines atleast one circular groove, and the wedges are partially received in theat least one groove.
 7. The wedge clutch of claim 1, wherein the wedgesare arranged in a plurality of wedge stacks that are circumferentiallyarranged around the inner race, each wedge stack including at least twoof the wedges that are axially spaced relative to each other.
 8. Thewedge clutch of claim 1, wherein the wedges include a first set ofwedges and a second set of wedges that alternate circumferentiallyaround the inner race.
 9. A wedge clutch comprising: an inner race; anouter race; and an annular wedge assembly radially disposed between theinner and outer races and configured to selectively couple the races,the wedge assembly including: a plurality of segments circumferentiallyarranged around the inner race, each segment having a pair of first andsecond wedge stacks interconnected to each other by a first link,wherein each of the wedge stacks has multiple wedges that are axiallyspaced relative to each other, and a plurality of second links that areeach connected between adjacent ones of the segments to interconnect thesegments to form a chain.
 10. The clutch of claim 9, wherein each of thefirst links includes pins on opposing ends of the link, and each of thewedges defines a first slot that receives one of the pins therein,wherein the slots are elongated in a circumferential direction of theclutch so that the wedge stacks are circumferentially movable relativeto each other.
 11. The clutch of claim 9, wherein each of the firstlinks includes an associated resilient member disposed between the pairof first and second wedge stacks and biasing the pair of wedge stacksaway from each other.
 12. The clutch of claim 11, wherein the resilientmembers are coil springs that circumscribe the first links.
 13. Theclutch of claim 9, wherein the inner race defines a plurality ofcircular grooves that are axially spaced to match axial spacing of thewedges of the wedge stacks, wherein the grooves receive inner surfacesof the wedges therein.
 14. The clutch of claim 13, wherein the outerrace defines an inner cam surface, and wherein the wedges have outersurfaces that match with sections of the inner cam surface such that thewedge stacks nest with the inner cam surface when rotationally alignedwith the sections and are urged radially inward to frictionally engagethe grooves of the inner race when rotationally misalign with thesections.
 15. The clutch of claim 9, wherein each of the wedge stacksfurther has spacers disposed between the wedges.
 16. A clutchcomprising: an inner race having an outer circumferential surfacedefining at least one groove; an outer race circumscribing the innerrace, the outer race having an inner circumferential surface defininglobes and valleys to form an inner cam surface; and a wedge chainradially disposed between the inner and outer races, the wedge chainincluding a plurality of wedges having inner edges disposed in the atleast one groove and interconnected with links to encircle the innerrace, each of the wedges having an outer surface that cooperates withthe cam surface to increase friction between the wedge and the at leastone groove in response to circumferential movement of the wedge towardsa corresponding one of the lobes and to decrease friction between thewedge and the at least one groove in response to circumferentialmovement of the wedge towards a corresponding one of the valleys. 17.The clutch of claim 16, wherein each of the wedges is connected to twolinks, and the wedges and the links are attached to each other such thatthe wedges are pivotal and circumferentially movable relative to eachother.
 18. The clutch of claim 16, wherein the links includes a firsttype of links and a second type of links.
 19. The clutch of claim 18,wherein the first type of links include resilient members.